Point lights cause flickering shadow artifacts

Hi,

Since I switched to unity 5 point lights cause some weird flickering black artifacts:

Or

I read a lot about similar issues and tried different fixes (playing around with the clipping planes, the cascades, shadow resolutions... even resizing the whole level as someone suggested that this might be caused by small geometry), but the bug is still there.

The weirdest thing is that it just appears at random. I build a level, everything is fine when I close unity and once I open it again the next day the artifacts appear. Sometimes they disappear for a few days and then bam! they're back again.

It is driving me crazy (the artifacts are visible in the build too). Does anyone have an idea or a similar issue?

(For info: i'm using Unity 5.2.0